#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001

void answer(int n){
	cout<<"! 1 "<<n<<endl;
	exit(0);
}

bool query(int N){
	cout<<"? "<<N<<endl;
	int ret;
	cin>>ret;
	if(ret*2 == N){
		answer(N);
	}
	if(ret*2>N)return true;
	else false;
	return true;
}


int main(){
	int N;
	cin>>N;
	
	bool f = query(2);
	N /= 2;
	int ok = N;
	int ng = 1;
	
	while(ok-ng>1){
		int mid = (ok+ng)/2;
		if(query(mid*2)==f)ng = mid;
		else ok = mid;
	}
	
	
	return 0;
}